let name = prompt('Who\'s there');

if (name == 'Admin') {
    let password = prompt('Password?');
    if (password == 'TheMaster') {
        alert("Welcome!");
    } else if (password == '' || password == null) {
        alert('Canceled');
    } else {
        alert("Wrong password");
    }
} else if (name == '' || name == null) {
    alert('Canceled');
} else {
    alert('I don\'t know you');
}